U.S. patent application number 11/507736 was filed with the patent office on 2006-12-14 for polystyrene blends and a method of making same.
This patent application is currently assigned to Fina Technology, Inc.. Invention is credited to Jose M. Sosa.
Application Number | 20060281869 11/507736 |
Document ID | / |
Family ID | 34376777 |
Filed Date | 2006-12-14 |
United States Patent
Application |
20060281869 |
Kind Code |
A1 |
Sosa; Jose M. |
December 14, 2006 |
Polystyrene blends and a method of making same
Abstract
Disclosed are blends of polystyrene and at least one of
syndiotactic polypropylene, ethylene propylene copolymers, and
styrene-butadiene-styrene triblock copolymers. These blends are
prepared using solution polymerization and have unique morphologies
and desirable physical properties. The blends can also be prepared
with graft-promoting or crosslinking agents and rubbers to prepare
modified high impact polystyrene.
Inventors: |
Sosa; Jose M.; (Deer Park,
TX) |
Correspondence
Address: |
FINA TECHNOLOGY INC
PO BOX 674412
HOUSTON
TX
77267-4412
US
|
Assignee: |
Fina Technology, Inc.
|
Family ID: |
34376777 |
Appl. No.: |
11/507736 |
Filed: |
August 23, 2006 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10674034 |
Sep 29, 2003 |
7129297 |
|
|
11507736 |
Aug 23, 2006 |
|
|
|
Current U.S.
Class: |
525/240 |
Current CPC
Class: |
C08K 5/14 20130101; C08L
25/06 20130101; C08L 23/12 20130101; C08L 25/06 20130101; C08L
23/08 20130101; C08L 2666/04 20130101; C08L 21/00 20130101; C08L
2205/03 20130101; C08L 2666/06 20130101; C08L 25/06 20130101 |
Class at
Publication: |
525/240 |
International
Class: |
C08L 23/04 20060101
C08L023/04 |
Claims
1-11. (canceled)
12. A polystyrene blend wherein the blend is a blend of
polystyrene, rubber, and a polymer selected from the group
consisting of syndiotactic polypropylene, ethylene propylene
copolymer, styrene-butadiene-styrene copolymers, and mixtures
thereof, and the blend is prepared by solution polymerization.
13. The polystyrene blend of claim 12 wherein the blend is composed
primarily of polystyrene and rubber and syndiotactic polypropylene,
and the weight ratio of polystyrene and rubber to syndiotactic
polypropylene, HIP:sPP, is from about 19:1 to about 4:1.
14. The polystyrene blend of claim 12 wherein the blend is composed
primarily of polystyrene and rubber and ethylene polypropylene
copolymer, the weight ratio of polystyrene and rubber to ethylene
polypropylene copolymer, HIP:EP, is from about 19:1 to about
4:1.
15. The polystyrene blend of claim 12 wherein the weight ratio of
polystyrene to rubber, PS:RUBBER, is from about 99:1 to about
7:1.
16. A process for preparing a polystyrene blend comprising admixing
styrene and a polymer selected from the group consisting of
syndiotactic polypropylene, ethylene propylene copolymer, and
mixtures thereof to form a solution, and then polymerizing the
styrene monomer.
17. The process of claim 16 wherein the process additionally
comprises using a solvent to increase the solubility of the polymer
in the styrene.
18. The process of claim 17 wherein the solvent is selected from
the group consisting of ethylbenzene, toluene, xylenes, and
cyclohexane and mixtures thereof.
19. The process of claim 16 additionally comprising using free
radical catalyst.
20. The process of claim 19 wherein the catalyst is a peroxide
catalysts selected from the group consisting of
1,1-di-(t-butylperoxy)cyclohexane;
1,1-di-(t-amylperoxy)cyclohexane;
1,1-di-(t-butylperoxy)-3,3,5-trimethyl-cyclohexane;
OO-t-amyl-O-(2-ethylbexyl monoperoxy-carbonate; OO-t-butyl
O-isopropyl monoperoxy-carbonate;
OO-t-butyl-O-(2-ethylhexyl)monoperoxy-carbonate;
N-butyl-4,4-di(t-butylperoxy)valerate; ethyl
3,3-Di-(t-butylperoxy)butyrate) and mixtures thereof.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates polystyrene blends. The
present invention particularly relates to polystyrene blends
prepared using a solution blend process.
[0003] 2. Background of the Art
[0004] Polystyrene is one of the largest volume thermoplastic
resins in commercial production today. Unmodified polystyrene is
well suited to applications where its brittleness is acceptable.
Engineering plastics have been used in applications where less
brittleness is required, but such polymers are often expensive or
have properties other than less brittleness that make them less
than optimum selections. Thus, styrene-based copolymers, and
particularly polystyrene resins that are modified with organic
rubber particles, have been investigated for use in applications
requiring less brittleness. The modification of polystyrene to
reduce brittleness is often referred to increasing its impact
properties and thus the modified polystyrene is said to have higher
impact.
[0005] These high-impact polystyrene blends, commonly referred to
by the acronym HIPS, are known to be useful in the art of preparing
articles with polymers wherein the application for the articles
requires less brittleness than unmodified polystyrene. For example,
U.S. Defensive Publication T59,011 to Smith discloses that a high
impact resin can be prepared by blending from 15 to 50 parts of an
impact modifier with from 85 to 50 parts of a clear crystal
polystyrene. Such materials are disclosed to be useful for
packaging applications.
[0006] Another method of making HIPS is to first dissolve a rubber
in styrene monomer and then polymerize the monomer. Such polymers
are disclosed in U.S. Pat. No. 6,569,941 to Sosa, et al. Therein,
it is disclosed that styrene monomer containing a dissolved
polybutadiene rubber is flowed into an elongated upflow stirred
reactor containing three reaction zones, wherein the styrene
monomer is polymerized to form a HIPS.
[0007] It is also known to blend polystyrene with other materials.
For example, U.S. Pat. No. 5,194,525, to Miura et al, discloses a
continuous process for making polystyrene from styrene monomer and
a polymerizable unsaturated fatty acid. The inclusion of the
unsaturated fatty acid is disclosed to improve the heat resistance
and moldability of the blend, making the modified polystyrene
desirable for injection molding applications.
[0008] In HIPS, desirably the polystyrene is a continuous phase
including a discontinuous phase of rubber particles. The size and
distribution of the rubber particles in the continuous polystyrene
phase can affect the properties of the HIPS. In blends of
polystyrene with other materials, the distribution of the
noncontinuous phase in the continuous polystyrene phase is often
similarly important.
SUMMARY OF THE INVENTION
[0009] In one aspect, the present invention is a polystyrene blend
wherein the blend is a blend of polystyrene and a polymer selected
from the group consisting of syndiotactic polypropylene, ethylene
propylene copolymer, and mixtures thereof, and the blend is
prepared by solution polymerization.
[0010] In another aspect, the present invention is a polystyrene
blend wherein the blend is a blend of polystyrene, rubber, and a
polymer selected from the group consisting of syndiotactic
polypropylene, ethylene propylene copolymer, hydrogenated styrene
butadiene copolymers, and mixtures thereof, and the blend is
prepared by solution polymerization.
[0011] In still another aspect, the present invention is a process
for preparing a polystyrene blend, the process including admixing
styrene and a polymer selected from the group consisting of
syndiotactic polypropylene, ethylene propylene copolymer, and
mixtures thereof to form a solution, and then polymerizing the
styrene monomer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] For a detailed understanding and better appreciation of the
present invention, reference should be made to the following
detailed description of the invention and the preferred
embodiments, taken in conjunction with the accompanying drawings,
wherein:
[0013] FIG. 1 is a photomicrograph made using transmission electron
microscopy (TEM) techniques of a polystyrene blend including 5
percent syndiotactic polystyrene and 6 percent rubber.
[0014] FIG. 2 is a TEM photomicrograph of a polystyrene blend
including 10 percent syndiotactic polystyrene and 6 percent
rubber.
[0015] FIG. 3 is a TEM photomicrograph of a polystyrene blend
including 10 percent syndiotactic polystyrene and no rubber.
[0016] FIG. 4 is a TEM photomicrograph of a polystyrene blend
including 10 percent ethylene propylene copolymer and no
rubber.
[0017] FIG. 5 is a TEM photomicrograph of a polystyrene blend
including 5 percent isotactic polystyrene and 4% polybutadiene.
[0018] FIG. 6 is a TEM photomicrograph of a polystyrene blend
including 10 percent isotactic polystyrene and 4%
polybutadiene.
[0019] It will be appreciated that the figures are not necessarily
to scale and the proportions of certain features are exaggerated to
show detail.
DETAILED DESCRIPTION OF INVENTION
[0020] In one embodiment, the present invention is a blend of
polystyrene and a polymer selected from the group consisting of
syndiotactic polypropylene, ethylene propylene copolymer,
styrene-butadiene-styrene copolymers, and mixtures thereof. In
another embodiment the blend additionally includes a rubber.
[0021] The polymers useful with the present invention are any that
are readily soluble in styrene at temperatures of from 30.degree.
C. to 100.degree. C. For purposes of the present invention, readily
soluble means soluble at a concentration of at least 15 weight
percent after stirring at about 110.degree. C. to about 1 hour. It
is desirable that the polymers be soluble at temperatures that are
sufficiently low to avoid thermal polymerization of polystyrene
during the dissolution process.
[0022] The syndiotactic polypropylene useful with the present
invention is any that is soluble in styrene at temperatures of from
about 30.degree. C. to 100.degree. C. For example, EOD-99-19 from
ATOFINA is such a material. In one embodiment the syndiotactic
polypropylene useful with the present invention has a melt flow
index according to ASTM D-1238 of from about 5 to about 50 g/10
minutes. In another embodiment, the syndiotactic polypropylene
useful with the present invention has a melt flow index of from
about 22 to about 27 g/10 minutes. In still another embodiment, the
syndiotactic polypropylene useful with the present invention has a
melt flow index of about 25 g/10 minutes. These materials can be
prepared using any catalysts system provided they meet the above
solubility and melt flow properties.
[0023] Ethylene propylene copolymers, random or impact, can also be
used with the present invention. Such copolymers can be prepared,
for example, by first performing a heterocatalyst polymerization of
a propylene feed followed by a feed of ethylene or a mixture of
propylene and ethylene. In the alternative, a compounded form of an
ethylene propylene copolymer can be used where an admixture of
polyethylene and polypropylene are first admixed and then
compounded to produce a copolymer. The ethylene propylene
copolymers useful with the present invention can have an ethylene
content of from about 0.1 to about 14 weight percent or even of
from about 4 to about 12 weight percent. In another embodiment, the
ethylene propylene copolymers useful with the present invention can
have an ethylene content of from about 6 to about 8 weight percent.
Commercially available ethylene propylene copolymers useful with
the method of the present invention include, but are not limited to
EOD-96-34, FINA6824 MZ, FINA4824 WZ, and FINA 7825 from ATOFINA.
Any ethylene propylene copolymers that are soluble in styrene at
temperatures of from about 30.degree. C. to 100.degree. C. can be
used with the present invention.
[0024] Certain styrene-butadiene-styrene triblock polymers can also
be used with the present invention. One such triblock polymer is
the KRATON G1600 series from KRATON POLYMERS. This material is a
linear styrene-(ethylene-butylene)-styrene triblock. Any such
polymer that is readily soluble in styrene as defined above can be
used with the process of the present invention. These materials can
be used either with or without removal of some or all residual
unsaturation.
[0025] In the practice of the method of the present invention of
preparing a polystyrene blend, a rubber is sometimes included in
the components of the polystyrene blend. Rubbers useful with the
method of the present invention include polybutadiene (PB), and
styrene-butadiene rubber (SBR). Natural rubbers can also be used.
Exemplary rubbers useful with the present invention include some of
the TARKENE.RTM. rubbers from BAYER and BUNA.RTM. EP rubbers from
BAYER. Any rubber that is soluble in styrene at temperatures of
from about 30.degree. C. to 100.degree. C. can be used with the
present invention.
[0026] The blends of the present invention are prepared by admixing
styrene and syndiotactic polypropylene, ethylene propylene
copolymer, and mixtures thereof. In a first embodiment of the
present invention, the polymers or mixture of polymers is soluble,
as defined above, in the styrene. In a second embodiment, a solvent
can also be used to increase the solubility of the polymers in the
styrene monomer. Suitable solvents include ethylbenzene, toluene,
xylenes, and cyclohexane and mixtures thereof. Any solvent useful
to facilitate the full or partial dissolution of rubber,
syndiotactic polystyrene, or ethylene propylene copolymer in
styrene monomer that can be removed after polymerization of the
styrene monomer and does not interfere with the polymerization of
the styrene monomer can be used with the method of the present
invention. In this embodiment of the present invention, the breadth
of polymers and rubbers useful with the present invention is
increased to include those polymers and rubbers that are soluble as
defined above in the solvent and styrene admixture.
[0027] In the practice of the process of the present invention, the
admixture of monomer and polymer or polymer mixture is further
admixed with a polymerization catalyst. This process is a solution
polymerization process. Exemplary catalysts include peroxide
catalysts such as, but not limited to Lupersol.RTM. 331
(1,1-di-(t-butylperoxy)cyclohexane Lupersol.RTM. 531
(1,1-di-(t-amylperoxy)cyclohexane); Lupersol 231
(1,1-di-(t-butylperoxy)-3,3,5-trimethyl-cyclohexane); Lupersol TAEC
(OO-t-amyl-O-(2-ethylbexyl monoperoxy-carbonate); Lupersol TBIC
(OO-t-butyl O-isopropyl monoperoxy-carbonate); Lupersol TBEC
(OO-t-butyl-O-(2-ethylhexyl)monoperoxy-carbonate); Trigonox.RTM. 17
(N-butyl-4,4-di(t-butylperoxy)valerate); and Lupersol 233 (Ethyl
3,3-Di-(t-butylperoxy)butyrate). Other catalysts that can be used
with the method of the present invention any peroxide having a
one-hour half-life of form 80.degree. C. to 160.degree..
[0028] The polymerization of the styrene monomer can be done using
any method known to be useful to those of ordinary skill in the art
of preparing polystyrene blends. For example, the polystyrene
blends can be prepared using an upflow reactor. The polymerization
process can be either continuous or done in batches. The
temperature ranges useful with process of the present invention can
be selected to be consistent with the operational characteristics
of the equipment used to perform the polymerization. In one
embodiment, the temperature range for the polymerization can be
from about 100.degree. C. to about 230.degree. C. In another
embodiment, the temperature range for the polymerization can be
from about 120.degree. C. to about 150.degree. C.
[0029] The blends of the present invention can also be prepared
using, as additional components, graft promoters, such as maleic
anhydride; chain transfer agents, such as dodecyl mercaptan; or a
crosslinking agent, such as divinyl benzene. Exemplary graft
promoting, chain transfer, and crosslinking agents include dodecyl
mercaptan, maleic anhydride and divinyl benzene, and mixtures
thereof. The use of such crosslinking agents with the process of
the present invention can increase the compatibility of the
components and further improve the properties of the blends made
therewith. When used, the graft-promoting crosslinking agent can be
used at levels of from about 100 to about 10,000 ppm. In one
embodiment of the present invention, the graft-promoting
crosslinking agent is used at levels of from about 1000 to about
8000 ppm. The use of a crosslinking agent can be useful in
polystyrene blends of the present invention wherein the blend does
not contain a rubber.
[0030] One embodiment of the present invention is a blend of
polystyrene with syndiotactic polypropylene. In styrene blends
where the blend is composed primarily of polystyrene and
syndiotactic polypropylene, the weight ratio of polystyrene to
syndiotactic polypropylene, PS:sPP, can be from about 19:1 to about
4:1. In another embodiment, the the weight ratio of polystyrene to
syndiotactic polypropylene, PS:sPP, can be from about 15:1 to about
10:1.
[0031] In another embodiment, the present invention is a blend of
polystyrene with ethylene propylene copolymer. In styrene blends
where the blend is composed primarily of polystyrene and ethylene
polypropylene copolymer, the weight ratio of polystyrene to
ethylene polypropylene copolymer, PS:EPC, can be from about 19:1 to
about 4:1. In another embodiment, the weight ratio of polystyrene
to ethylene polypropylene copolymer, PS:EPC, can be from about 15:1
to about 10:1.
[0032] In still another embodiment, the present invention is a
blend of a high impact polystyrene, that is a mixture of rubber and
styrene, with syndiotactic polypropylene. In styrene blends where
the blend is composed primarily of HIP and syndiotactic
polypropylene, the weight ratio of HIP to syndiotactic
polypropylene, HIP:sPP, can be from about 19:1 to about 4:1. In
another embodiment, the the weight ratio of polystyrene to
syndiotactic polypropylene, PS:sPP, can be from about 15:1 to about
10:1
[0033] In another embodiment, the present invention is a blend of
polystyrene with HIP. In styrene blends where the blend is composed
primarily of HIP and ethylene polypropylene copolymer, the weight
ratio of HIP to ethylene polypropylene copolymer, HIP:EP, can be
from about 19:1 to about 4:1. In another embodiment, the weight
ratio of polystyrene to ethylene polypropylene copolymer, PS:EP,
can be from about 15:1 to about 10:1.
[0034] When the polystyrene blend is a HIP blend, the weight ratio
of polystyrene to rubber, PS:RUBBER, is from about 99:1 to about
7:1. In another embodiment, the weight ratio of polystyrene to
rubber, PS:RUBBER, can be from about 19:1 to about 10:1. Included
in the term "rubber" are any of the materials already described
above.
[0035] One advantage of a blend over unmodified polystyrene is that
it can have better impact properties and can also retain blowing
agents, such as carbon dioxide in foam applications. Another
application of the compositions of the present invention is in the
use of containers in contact with food items such as salad oil. The
blends of the present invention also compare favorably to
conventional HIPS. The blends of the present invention can have
morphologies that have better dispersion of the non-continuous
phase within the continuous polystyrene phase. Preferably, the
non-continuous components are evenly distributed, intermixed and
exist as spheres rather than as elongated cylinders within the
continuous polystyrene phase of the blends. This effect can be
enhanced using graft-promoting agents, such as maleic anhydride.
The net effect of using polyolefins is to modify the impact and
solvent properties of the polystyrene composites. Increased
ductility is obtained by enhancing the rubber phase volume of the
composite.
[0036] The polystyrene blends of the present invention can be
prepared using additives. Exemplary additives include fillers such
as talc, anti-oxidants, UV stabilizers, mineral oil, and the like.
Any additive known to be useful in preparing polystyrene blends to
those of ordinary skill in the art of preparing such blends can be
used with the present invention.
[0037] In an embodiment of the present invention wherein there is
residual monomer at the end of the polymerization of the styrene
monomer, the monomer can be removed from the polystyrene blend. In
embodiments where a solvent is used, the solvent can be removed
from the polystyrene blend. Any method of removing unreacted
styrene monomer and solvent, if any, known to be useful can to
those of ordinary skill in the art of manufacturing polymer blends
can be used with the method of the present invention. After
removal, the solvent and styrene monomer can be recycled or
discarded.
EXAMPLES
[0038] The following examples are provided to illustrate the
present invention. The examples are not intended to limit the scope
of the present invention and they should not be so interpreted.
Amounts are in weight parts or weight percentages unless otherwise
indicated.
Example 1
[0039] A HIP polystyrene blend is prepared by dissolving 5 percent
of a syndiotactic polypropylene sold under the trade designation
EOD 99-19 by ATOFINA and 6 percent of a percent rubber sold under
the trade designation TAKTENE.RTM. 550 T by BAYER in styrene
monomer at 110.degree. C. 300 ppm Lupersol.RTM. (L-531, 100 ppm
Lupersol L-233 and 400 ppm maleic anhydride are added and the
solution held at 110.degree. C. for 120 minutes. The admixture
temperature is raised to 130.degree. C. and held for 60 minutes.
The admixture temperature is raised to 150.degree. C. and held for
60 minutes. During the course of and at the end of the heating
periods, samples are removed and devolatized at 225.degree. C. for
25 minutes at a pressure of 0.8 torr (107 Pascal). The solids level
in the samples is about 70%. A sample of the final polymer is
subjected to transmission electron microscopy to prepare a
photomicrograph that is shown below as FIG. 1. It takes about 5-10
minutes for dissolution of the syndiotactic polypropylene in the
styrene monomer.
Example 2
[0040] Example 1 is repeated and tested substantially identically
except that 10 percent syndiotactic polypropylene is used and the
TEM photomicrograph is shown below as FIG. 2.
[0041] An examination of the electron photomicrographs of the
polymers of Example 1 and Example 2 (FIGS. 1 & 2) shows that
the polymers (101 & 201) have a continuous polystyrene phase
(102 & 202) and, distributed therein, inclusions of
syndiotactic polystyrene and polybutadiene. These inclusions
consist of primarily two types. A first type (103 & 203)
consists of a honeycomb type structure of black polybutadiene and
syndiotactic polystyrene. A second structure (104 & 204)
consists of a sphere of syndiotactic polystyrene surrounded by a
layer or membrane of black polybutadiene.
Examples 3-6
[0042] The procedure of Example 1 is repeated substantially
identically except that components are varied as shown below in
Table 1. The samples, prior to being devolatilizing, are analyzed
for physical properties and the results as displayed below in Table
1. TABLE-US-00001 TABLE 1 Formulations and Results of HIPS Prepared
in the Presence of Syndiotactic Polypropylene And Ethylene
Propylene Copolymer And Maleic Anhydride Example 3 Example 4
Example 5 Example 6 Feed % Syndiotactic 5 10 Polypropylene.sup.1 %
Ethylene 5 10 Propylene Copolymer.sup.2 % Rubber.sup.3 8 8 8 8
Maleic 1200 1200 400 400 Anhydride (PPM) Lupersol 531 300 300 300
300 (PPM) Lupersol 233 100 100 100 100 (PPM) Properties RPS
microns.sup.4 9.0 7.9 2.8 2.4 % rubber.sup.5 16.5 15.4 6.6 6.4 %
sPP or EP.sup.6 10.4 19.3 6.1 12.5 % gels.sup.7 43.8 47.4 18.9 22.4
Swell Index.sup.8 7.7 7.9 11.7 8.2 Gel/rubber.sup.9 2.7 3.1 2.9 3.5
DMA.sup.10 rubber Tg .degree. C. -85.4, 2.0 -86.6 -87.1, -14.4 Tan
delta 0.11, 0.053 0.049 0.041, 0.028 EOD 99-19 is a syndiotactic
polypropylene having a MFI of 12 available from ATOFINA. EOD 94-21
is an ethylene propylene copolymer having a MFI of 12-35 available
from ATOFINA. TAKTENE 550 T is a polybutylene rubber having a
Mooney Viscosity of 48-55 available from BAYER. .sup.4-10Test
methods. RPS, rubber particle size, is obtained via Malvern
Particle Size Analyzer in methyl ethyl ketone; % rubber is obtained
by titration with iodine monochloride; % sPP or EP in the product
is obtained by calculation as follows: a) % sPP or EP in the
feed/1.0 - unreacted styrene; b) swell index # is obtained by
dissolving samples in toluene, separating the gel phase by
centrifugation, and obtaining the ratio of the wet gel to dry gel;
c) gel/rubber ratio is obtained by calculation from parameters
shown within the table, and d) Tg and tan delta values are obtained
by using a Rheometrics .RTM. RDA II dynamic mechanical
analyzer.
Examples 7-12
[0043] The procedure of Example 1 is repeated substantially
identically except that components are varied as shown below in
Table 1. The samples, prior to being devolatilizing, are analyzed
for physical properties and the results as displayed below in Table
2. TABLE-US-00002 TABLE 2 Formulation and Results of HIPS Syntheses
in the Presence of Syndiotactic Polypropylene, sPP, and Ethylene
Propylene Copolymer, EP, and Maleic Anhydride, MA. Example 7 8 9 10
11 12 Formulation % sPP.sup.1 12 12 12 % EP.sup.2 12 12 12 %
Rubber.sup.3 4 4 4 4 4 4 Lupersol 300 300 300 300 300 300 L-531 PPM
Lupersol 100 100 100 100 100 100 L-233 PPM MA PPM 2000 4000 8000
2000 4000 8000 Pellet Properties % Rubber 6.5 6.3 7.0 6.3 6.3 7.4
RPS.sup.4 5.7 6.9 6.6 2.5 2.8 3.4 % Gel.sup.5 36.5 39.2 38.4 27.5
34.0 38.7 Swell Index.sup.6 5.2 4.9 5.3 5.9 4.7 4.2
Gel/Rubber.sup.7 5.6 5.77 5.5 4.4 5.4 5.2 Gel/ 2.0 2.1 2.0 1.5 1.9
2.0 (% PB + PO).sup.8 Mn (000).sup.9 112 103 106 88 105 84 Mw
(000).sup.10 258 235 248 231 247 210 MWD.sup.11 2.3 2.3 2.3 2.6 2.4
2.5 .sup.1-11See Table 1
Example 13
[0044] A polystyrene blend is prepared by dissolving 10 percent
syndiotactic polypropylene, sold under the trade designation
EOD-94-21 by ATOFINA, in styrene monomer at 110.degree. C. 300 ppm
Lupersol L-531, 100 ppm Lupersol L-233 and 8000 ppm maleic
anhydride are added and the solution held at 110.degree. C. for 120
minutes. The admixture temperature is raised to 130.degree. C. and
held for 60 minutes. The admixture temperature is raised to
150.degree. C. and held for 60 minutes. During the course of and at
the end of the heating periods, samples are removed and devolatized
at 225.degree. C. for 25 minutes at a pressure of 0.8 torr (107
Pascal). The solids level in the samples is about 70%. A sample of
the final polymer is subjected to transmission electron microscopy
to prepare a photomicrograph that is shown below as FIG. 3.
[0045] The morphology of the photomicrograph of Example 13 (FIG. 3)
shows that in a polystyrene blend with syndiotactic polypropylene
(301), the syndiotactic distributes as small spheres (303) having
entrapped polystyrene (304) in a continuous polystyrene phase
(302). Note that no rubber is used.
Example 14
[0046] A polystyrene blend is prepared by dissolving 10 percent
ethylene propylene copolymer [details . . . either product name or
else property listing] in styrene monomer at 110.degree. C. 300 ppm
Lupersol L-531, 100 ppm Lupersol L-233 and 8000 ppm maleic
anhydride are added and the solution held at 110.degree. C. for 120
minutes. The admixture temperature is raised to 130.degree. C. and
held for 60 minutes. The admixture temperature is raised to
150.degree. C. and held for 60 minutes. During the course of and at
the end of the heating periods, samples are removed and devolatized
at 225.degree. C. for 25 minutes at a pressure of 0.8 torr (107
Pascal). The solids level in the samples is about 70%. A sample of
the final polymer is subjected to transmission electron microscopy
to prepare a photomicrograph that is shown below as FIG. 4.
[0047] The morphology of the photomicrograph of Example 14 (FIG. 4)
shows that in a blend of polystyrene and ethylene propylene
copolymer (401) the ethylene propylene copolymer distributes as
larger spheres, generally not having entrapped polystyrene (403),
in a continuous polystyrene phase (402).
Comparative Examples I & II
[0048] Examples 1 and 2 are repeated substantially identically
except that an isotactic polypropylene, sold under the trade
designation FINA4621 is used, is used. Samples of the final
polymers are subjected to transmission electron microscopy to
prepare a photomicrograph that is shown below as FIG. 5 for
Comparative Example I which has 5 percent isotactic polypropylene,
and FIG. 6 for Comparative Example II which has 10 percent
isotactic polypropylene. It takes about 20-30 minutes to dissolve
the isotactic polypropylene in the styrene monomer.
[0049] An examination of the photomicrographs of the polymers of
Comparative Examples I & II (FIGS. 5 & 6) shows that in a
styrene blend of isotactic polypropylene (501 & 601), the
isotactic polypropylene form irregular pools (503 & 603) in a
continuous polystyrene phase (502 & 602).
* * * * *